Question

I have 1 unit test method that needs several parameters. I would like to run this test once for every possible value of a cartesian with a predefined list for each parameter. I imagine that parameters could be passes in via the test context, but I do not want to connect to an external database.

For example: If I had 2 parameters with the following possible values, the test would execute 6 times (order doesn’t matter). (pseudo-code)

p1 = { 1, 5, 10 }
p2 = { "blue", "red" }

test 1: ( 1, "red" )
test 2: ( 5, "red" )
test 3: ( 10, "red" )
test 4: ( 1, "blue" )
test 5: ( 5, "blue" )
test 6: ( 10, "blue" )

Note: I’m using the built-in Visual Studio 2010 unit testing, not NUnit or one of the many other unit test frameworks.

Edit:

I’m storing the possible values as enumerations in the test class, but it is also reasonable to use arrays. My goal is to automate the link between the source enumerations/arrays and the actual test. While my sample only has 2 parameters with 6 permutations, the actual set is much larger. I do not want to skip a scenerio just because I missed something in a manual conversion.

Answer 1

The answer to your question is: You can use “Data-driven tests”. You can store your values in comma-seperated-value files, XML files, or SQL database files. I’ve been doing this with VS2k8, so your process with VS2k10 may be a little bit different.

First, create a file with your test data. If you create a CSV file, it might look like

param1, param2
1, blue
1, red
5, blue
5, red
10, red
10, blue

Go to “Test View”, select the test you want to use the data with. In properties, click the ellipsis dots next to “Data Connection String”. Specify your file.

Now, in your unit test code, you will specify the data from your file as
testContext.DataRow("param1") and testContext.DataRow("param2").

When you run the test, you will get a test result for each data row the test runs with. How convenient!

Update If you want to automatically use Cartesian products of parameters that are kept as enumerations, you might want to use nested for loops like

dim testResults as dictionary(of triplet,string)
for each x as foo in fooCollection
for each y as bar in barCollection
for each z as foobar in foobarCollection
Try
‘ test code
testResults.add(new triplet(x,y,z),”PASS”)
catch ex as exception
testResults.add(new triplet(x,y,z),”ERROR: ” + ex.toString())
End try